| 摘要 |
PROBLEM TO BE SOLVED: To provide a liquid crystal display device and a surface light source for backlight permitting to efficiently use a light source and external light, and a light guide plate possessed by the surface light source, by considering the main purpose of the liquid crystal display device. SOLUTION: A light intake part 1a is formed by resin-molding in a light guide body 1 by using a die. A cross-section 1f of the light guide body 1 is designed so that it is approximately wedge-shaped getting narrower to the left and an area of the external light intake part 1a is smaller than that of the light incident plane 1c. The reason for this is that light quantity of external light such as the sunlight is so large that sufficiently bright light can be emitted from a light emitting surface 1e without increasing an area of an external light intake part 1a. On the other hand, a light incident plane 1c has a large area enough to efficiently take in the light emitted from the light source 3. When the light source is turned on, the light from the light source made incident from the light incident plane 1c and the external light made incident from the external light intake part 1a are reflected by the reflection plane 1d and the two side faces 1b of the light guide plate 1, and the diffused radiation light guided in the direction of the light emitting surface 1e is made to exit from light emitting surface 1e as combined light having uniform directivity within a desired angular range. |
